Children of the Planet
by Masu Trout
Summary: Midgar is in ruins, humanity is suffering, and the Planet is being wracked by an illness no one can cure. Sephiroth has only one goal: find Aerith Gainsborough, the last living Cetra, before it's too late. [Canon-divergent AU, Gen]


The Forgotten Capital was solemn and still, quieter than any place Sephiroth had traveled to before.

It was everything Midgar wasn't–the place he'd once called his home city was a constant bustle of noise and life, an eternally-changing marvel that was only too happy to toss aside the past for the excitement of a better future. Its instability had always frustrated Sephiroth.

This place, though, was making him miss Midgar.

The thick dust muffled his footsteps as he stepped through yet another empty room. The artistry and skill apparent in every building was almost breathtaking–even the smallest and plainest of them would have sold for millions of gil in Midgar. The lifelessness of the city, though, gave its beauty an eerie tone; it reminded Sephiroth of the ancient kings and pharaohs he'd read about as a child, shut away in their stone tombs.

He couldn't stop thinking about what it must have been like once, when every house was filled.

"Hey, Sephiroth!" Zack's voice, always loud and louder still here, echoed across the rooftops. "Have you found anything?"

Sephiroth peered outside. Zack stood outside a house near the one Sephiroth had been investigating, leaning against the doorway.

"I haven't yet," Sephiroth admitted. "Nothing I think is relevant, anyway." This whole place was fascinating–in another life he would have loved to study it. "How about yourself?"

Zack shrugged. "I'm not sure, actually… I mean, it's something, but it's really weird. I don't know if it means anything."

Zack normally had fantastic instincts; if he thought there was something even potentially important, it might well end up being vital to them.

"Show me," Sephiroth said.

Zack led him into the house he'd been exploring, then over to the corner of what might once have been a kitchen. There, on the floor, was a strange shimmering substance. It had the shape of a bubble of mercury, but shone even brighter than mako. The surface gleamed white and strange shapes seemed to twist within its depths- Sephiroth felt as though he could make them out if only he leaned a little closer.

"I poked at it," Zack said, "But nothing happened." He laughed. "Well, unless it's poison, and I just haven't keeled over yet.

Sephiroth sighed. He'd always assumed Zack would get at least a _little_ more cautious with age, but his near-suicidal curiosity was apparently non-temperable.

Sephiroth reached out one finger and gently prodded the surface of the shallow pool.

 _It was not yet noon, and the capital's square bustled with people from every corner of the world. Merchants stood in the shade of buildings or the mouths of alleyways, hawking their wares with an almost desperate zeal, but they went ignored. Today, the splendor of the capital was but an afterthought in people's minds._

 _Already, the monstrosity had killed a thousand of their people. Tomorrow, it might kill a thousand more. People had begun to flock here in droves, desperate for news on how they would kill the monstrosity. (And, some of them whispered, whether it could be killed at all.)_

 _The Cetra had gathered, searching for answers, but still the palace doors remained shut._

Sephiroth pulled back with a gasp. His heart raced, his vision was blurred, and his hands were trembling. The memories of the Cetra pulsed through him–he could feel their fear, their willingness to fight.

"Sephiroth?" Zack asked worriedly. His voice was like an anchor; Sephiroth let it steady him against the current of these strangers' emotions.

He wasn't one of them, he reminded himself. No matter what he'd believed, no matter what _she'd_ told him, he wasn't (couldn't be) one of their people. He was more a part of the monster they feared than he was the Cetra.

Sephiroth stood, shaking Zack's hand off his shoulder.

"I'm fine," he said, more sharply than he'd intended. He took a breath, forced his heartbeat to calm. He might not have been SOLDIER any longer, but he was still a soldier. "It took me by surprise, that's all."

Zack frowned. "So what is it, then?"

"It's... memories. Memories of the Cetra, condensed into a liquid form."

Zack started. "Does that mean-" He broke off, glanced at the liquid once again. "Do you think Aerith's the one who made them, then?"

He was trying hard to look casual, but Sephiroth could see the tension in his body as he shifted back and forth.

"No," he said. "These are much older. I think they're from the ones who once lived here."

Zack sighed.

"We'll find her," Sephiroth said firmly.

"Yeah." Zack smiled at him. "You're right. I'm sure we will."

Together they searched the ruined city. It was a strangely pristine place; there was no sign of destruction or upset, no clue as to what could have forced an entire city of people to leave or die. Many of the houses still had small trinkets or simple dishware laid out, as if the family inside had simply walked out into the night and left everything behind.

It made no sense.

Four times more they came across the small silvery pools. They were like beacons to Sephiroth; maybe they could explain the Cetra's fate or give him more insight into what Aerith's plan might be. But each time he stopped before the pool, unable to reach out and connect with the ancient memories. His breath would quicken again, his heart would race, and after a time he would pull away.

Shameful as it was, he was afraid. He knew what the Cetra had fought, and he knew the kind of destruction that monster could cause-

 _(the destruction he'd once caused for her)_

-and he didn't want to see that creature ever again.

Zack must have noticed his hesitation, but he didn't say anything. As exuberant as he was, he could be surprisingly tactful sometimes.

It wasn't until the sun was going down, throwing long shadows across the city, that Zack looked up from their work.

"We should join up with the others. I think I saw a building back there that had something kinda bed-like left. It would be nice not to sleep in tents again, right?"

"I'm not tired."

Zack rolled his eyes. "Come on, it's getting dark and we don't know what's out here."

"Zack, we're SOLDIERs."

" _Ex-_ SOLDIERS."

"Nonetheless," Sephiroth replied. "We can see in the dark. And there's not likely to be anything here that can stand up to us."

Zack sighed and pinched the bridge of his nose. "Sephiroth. Just because we _can_ do something doesn't mean we should. When's the last time you got more than four hours of sleep?"

Sephiroth scowled. Zack was always so fussy about his health. It was a pointless thing to fret over–he'd been bred and designed to work in far harsher conditions than these.

"Look," Zack said. "I know you want to find Aerith." He bit his lip, glanced towards the ground. "Trust me, I do too. But there's no point in you driving yourself like this."

"If we find Aerith-"

"If we find Aerith, it will be because she wants to be found. This is the Ancients' city; there's no way for us to know it like she does."

They were so close. When they'd first picked up her trail, it had been little more than a rumor–a girl in pink had been to North Corel, no, Junon, no, Mideel–for a while they hadn't been sure she was out here at all. It was entirely possible that her disappearance had been a red herring; she very well could have died within Midgar like so many others.

Eventually, though, rumors had turned to hearsay and hearsay had become sightings. They _knew_ she had come to this city only days ago; if they lost her once again he wouldn't be able to forgive himself.

Sephiroth's mind flashed guiltily the pools of memory. Surely it meant something that they'd permitted him to see that? Perhaps he was meant to delve into the glimmering drops, search out the secrets of the city. Find the path that Aerith had taken, even if it pained him.

"The Cetra memories," he said reluctantly. "If I look within them-"

" _No!_ "

Sephiroth blinked, shocked by the viciousness with which Zack had snarled the word.

"Absolutely not," Zack snapped. "Sephiroth, those were _hurting you_. You can't just throw yourself into any kind of danger because you think you'll survive it!"

"You think I won't, then? That I'm not strong enough?" The words slipped out without thinking, loud and angry. He hadn't meant to raise his voice like that.

Zack' breath caught. He slumped, and the anger drained out of him. "That's not it. I promise you, Sephiroth, that's not it at all. I've never thought you were weak."

Sephiroth shifted, sudden guilt crawling through him. "I didn't mean to say that." Zack was one of the few people he'd ever known who neither looked up to him nor down to him, but considered him an equal. A friend, even, though what Zack wanted with a friend like him he'd never been able to understand.

Zack sighed. "I'm the one who should be sorry." He smiled at Sephiroth; the expression was small, but no less genuine for it. "I know you can make it through, but that doesn't mean I like to see you getting hurt."

Sephiroth nodded–he didn't know how to respond to that properly. Finally, he said. "On second thought, I think you're right. We should collect our group and find a place to rest for the night."

Despite what Shinra's higher-ups used to say, he wasn't completely inflexible. He just hoped Zack knew to take it for the apology it was.

"All right!" Zack smiled widely and pulled out his PHS. "I'm so ready to have a proper roof over my head."

It had to be an act, at least somewhat; even Zack didn't bounce back that quickly. But Sephiroth was more than happy to pretend not to see that.

* * *

They met up with Vincent and Lucrecia near the entrance to the towering amphitheatre. Vincent nodded at him, face obscured by his cowl, and Lucrecia stepped forward. Her fingers twitched briefly, as though she were going to reach out to him but had decided against it.

"Have you found anything?" she asked. Her gaze was fixed on a point slightly above him and to his left.

Sephiroth shook his head. "We found some artifacts, and some sort of liquid, but…" He trailed off, unsure how to finish his sentence. Unsure how much he wanted this stranger who called herself his mother to know.

In the end, Zack rescued him. "We couldn't do anything with it, and we didn't want to touch it just in case. I may have, uh, poked at it a bit, though."

Lucrecia smiled faintly. "Yes, we found much the same. I doubt you'll suffer any ill effects from the solution–Vincent says it seems very old, and likely harmless."

"Oh?" Sephiroth asked.

Vincent stepped forward, joining the conversation. "Correct. I could sense only that much, however." That wasn't uncommon for him; the monsters in his head tended to be cooperative only insofar as it kept their host alive.

"I wish we could be here on other business," Lucrecia said softly. "There is so much here I would love to study, given the time." Her smile turned inward, distant.

"I know what you mean. It's a fascinating city."

Lucrecia was a strange woman, Sephiroth thought. Her demeanor was bizarrely docile for someone with as terrifyingly sharp a mind as hers. Often during conversation she would gaze off into the distance, seeming to be in her own world entirely, only to rejoin their discussion with some important information or well-thought-out plan.

He couldn't help but wonder if she had always been this way, or if this was some personality trait she had gained while encased in her crystal cocoon. He'd been meaning to ask Vincent for some time, but the man could be frustratingly hard to start a conversation with. Sephiroth had gained some sympathy for the people back in Shinra who complained about his own taciturn nature.

"Well!" Zack said brightly. "We thought it would be a good idea to find somewhere to rest for the night. I think I found a building that would work well."

"That's fine with me," Lucrecia said, and Vincent's lack of objection was agreement enough.

Zack led the way through the winding streets of the city, past dozens of small buildings. Each was entirely unique: some were made entirely of seastone, others had roofs carved from enormous conch shells, and still others had walls embedded with fossilized shells and windows studded with jewel-bright sea glass. As they went, he chattered freely about the things they'd seen within; the creek that ran through one house, the carved-glass fish statue within another. Not for the first time, Sephiroth found himself envious of Zack's open nature. Despite having three quiet companions, he never seemed uncomfortable.

Finally, they arrived at the house Zack had mentioned. It had been built within one of the conch shells and wound tightly around itself. The floor was made of sturdy wood, still unrotting after thousands of years, and there were indeed something approaching beds made of a light, springy wood on the second floor. It wasn't quite on the level of Midgar's comforts, but once they'd laid their bedrolls on top it was pleasant enough–certainly, Sephiroth thought, better than another night spent on the hard-packed dirt.

They ate quickly and quietly. Sephiroth was surprised to realize that he was actually very hungry; even the rations tasted almost decent.

There was a sense of foreboding in the air, a crawling feeling that crept down Sephiroth's spine. It occurred to him that, no matter how desperately he'd searched for Aerith, he'd never truly believed he might not find her. She was waiting for him here, somewhere within the Forgotten Capital, and it was only a matter of time before they came face to face.

He knew little about the woman except what Zack and Tseng had told him, and each of them was biased in their own way. Zack said she'd been a beautiful, vibrant woman, with a cheerful smile and a kind word for anyone; he was so very sure she could not have done what she was accused of, that there must be some misunderstanding. Tseng had been much less revealing (unsurprising, considering his personality and the circumstances involved), but he had spoken of a powerful girl with a love for humanity, one who bore a great sense of responsibility and a greater sense of mercy. It had been clear that he, too, assumed Aerith's innocence.

Sephiroth didn't know what to believe. He trusted Zack more than he trusted even himself. But he couldn't forget what he'd seen (who he'd seen) standing in the heart of the vibrant and dying Midgar.

He had no right to judge, not after what he'd done to Wutai, to Nibelheim. But if she was truly a danger to humanity, then he would be her executioner.

Zack brushed the back of his hand lightly, bringing him out of his stupor. Sephiroth started; he'd been staring at his empty ration bar wrapper for the past few minutes.

"We've got more, if you're still hungry." Zack grinned, waved another packet at him. "Three different delicious flavors."

"Cardboard, mud, or tree bark," Sephiroth finished. It was a common joke from the Wutai War, though not a particularly accurate one–he'd eaten tree bark before, and it was actually fairly tasty. "Thank you, but I'm fine. Just…" He trailed off, unsure how to finish his sentence.

"Tired?" Zack asked.

Sephiroth nodded. It was a close enough answer to the truth.

"Yeah, me too." Zack yawned. "Hard to believe it's barely nine o'clock."

"It may be early, but we should all rest." Vincent cut in quietly.

Lucrecia nodded. "The earlier we wake, the better–there might be clues we can find more easily with changed lighting." She glanced at him as she spoke, concern in her eyes.

Sephiroth shifted uncomfortably. He wasn't used to having a mother, didn't understand how to respond to her worry.

"I agree," he said shortly, and that was the end of the conversation.

* * *

Sleep did not come easy for Sephiroth.

He'd claimed the bed nearest to the wall, and let Zack take the one next to him. Zack's presence was always a great comfort; the glint of the Buster Sword in the dim light, the evenness of his breathing, and the soft noises as he shifted in his sleep were familiarities even in this strange place.

Sephiroth breathed slowly, trying to match his own breathing to Zack's. No matter where they slept, be it a luxury hotel or a muddy trench, Zack somehow managed to doze off the moment he was horizontal.

Here, especially, his friend's presence felt like a shield. It was embarrassing to admit–even if Vincent or Lucrecia were to betray him, he could almost certainly overpower either–but his newest allies made him uncomfortable. Both seemed to feel some sort of guilt over him; their stilted attempts at sympathy always left him feeling awkward.

Though, he reminded himself, he had no room to complain. It was he who'd gathered the two and allowed them (asked them) to join Zack and himself on their journey. More hands were always helpful, and he certainly could have chosen himself worse allies.

He shifted quietly, begging for sleep to come. The tension that had plagued him all day refused to unravel, and his thoughts wouldn't stop wandering. On Zack's other side, Lucrecia was snoring softly, and Vincent… well, Sephiroth wasn't sure the man _slept_ at all, exactly–his eyes didn't close and his behavior reminded Sephiroth more of someone in a meditative state–but he was still and his breathing had evened out.

It was Vincent he'd found first. He'd travelled to Nibelheim, the scene of his every nightmare, in hopes of finding the answers his father wouldn't give him. (And, though he'd never admit it to anyone, to pay his respects to the innocent dead.) He'd wanted to know who–what–he was, and just what evil he might be capable of.

He hadn't expected, though, to find a village where he'd left only ash. And he _certainly_ hadn't expected the man he'd found sleeping in the carcass of Shinra's oldest research lab.

The things Vincent had told him had been beyond painful to hear. He'd never assumed he was born from something like love, but… he'd cared for professor Gast. Trusted him and the harmony he believed in. Sephiroth had always assumed he was created to help humanity, and that the way he'd turned out was merely some horrid mistake.

To realize otherwise, to understand just what had gone into his creation, had been a blow. To find out he'd had a _mother_ –a real, human mother, so unlike the one he'd answered to before–had been far more painful.

And then to realize she might still be _alive_... it was embarrassing, even now, to admit how strongly he'd reacted.

He'd found Lucrecia only barely a month ago, encased in crystal and entombed within a cave that even two first-class SOLDIERS and the all-but-weightless Vincent had trouble reaching. Vincent had led him and Zack there, or perhaps Sephiroth had led them both–Sephiroth no longer remembered the details. That time was a blurry smudge of desperation and weariness and hope in his memory.

Sephiroth had broken apart the crystal with his own two hands, and the three of them together had pulled her, weak and shaking, from her shell.

The first week she'd spent all but incoherent, caught between the waking world and her feverish dreams. Sometimes, she'd spoken to Sephiroth as though she knew more about him than he did, and other days she seemed unable to recognize him at all.

Vincent had been an unexpected help during that week; he'd stayed by Lucrecia's side constantly.

The problem with having a human mother, he thought, was that he was completely unsure how to act around one. A father would have been possible–thanks to Professor Gast, he at least had some idea what that was like–but after all this time even a normal mother would have been difficult, and Lucrecia was anything but.

As a scientist and an ex-Shinra employee, she was invaluable. As a parent… well. The two of them had barely discussed their relationship thus far, despite some subtle suggestion on Vincent's part and some less-than-subtle urging on Zack's.

Sephiroth had no idea how he felt about her. She seemed to care for him somewhat–at the very least, she didn't hate him outright. It didn't make sense to him; he couldn't reconcile this woman with the one who'd agreed to give birth to a science experiment, and then tried to kill herself as penance for creating him.

She didn't deny it, and he hadn't asked her to defend her choices. Frankly, he wasn't sure he was willing to hear what she might say.

Eventually they would talk, he hoped. But they could do that later, when the world was stable; now was no time for him to have (another) identity crisis.

Sephiroth sighed heavily and slipped out of his bedroll. Sleep obviously wasn't coming naturally any time soon. He stepped quietly across the room, the worn wood cool beneath his feet, and rummaged in his pack until his fingers closed around a seal materia. Artificial sleep was never as refreshing as the natural sort, but a quick cast of sleepel would at least give him a few hours' worth.

Before he could return to his bed, though, he was struck upside the head by a deep and overwhelming sense of _wrongness_. It was chilling and choking and, worst of all, it was intimately familiar.

 _Jenova._

He scanned the room wildly, trying to remember where he'd set Masamune, only to realize the sword was already in his hand.

This was no good. She was already messing with his head, and she–probably–wasn't even trying yet.

"Zack," Sephiroth snarled.

Zack didn't so much as yawn; he went from a dead sleep to completely awake in the time it took to blink. He grabbed the Buster Sword and rolled out of bed in one fluid motion.

"Sephiroth," he said. "What's wrong?"

"She's here."

Behind him, Lucrecia and Vincent stirred, woken by the commotion.

Zack lowered the tip of the Buster Sword. "Aerith? Where is she?"

Sephiroth shook his head. "The other 'she'."

The excitement drained from Zack's face and was quickly replaced by dread. "How..?"

"I don't know. But I feel her."

Three years ago, in the Nibelheim Reactor, Zack had turned Jenova to ash while a trooper–Zack's friend–pinned Sephiroth to the wall with his own sword. He'd assumed (foolishly; how could he have been so stupid?) that the destruction of her physical body would be the end of her.

And yet she was here, in the City of the Ancients. Taunting him with her presence, daring him to find her.

"Vincent," he said hoarsely. "If I make any attempt to attack one of you, shoot me."

Vincent nodded and slipped his gun from his holster. "Understood."

"Sephiroth," Zack protested.

Sephiroth glared at him. "I won't kill anyone else."

Zack hesitated a moment, then nodded. "Yeah," he said. "I get it. Just… be careful, okay?"

"I will." Sephiroth glanced between his three companions. "Okay. Let's go."

* * *

Her presence prickled under his skin as he followed her trail. Zack, Vincent, and Lucrecia trailed behind him as he walked through the shadowed ruins.

Before long, he found himself in front of one of the buildings they'd explored the day before: the twisted and lopsided conch that had held the fish statue.

Sephiroth blinked as he stepped into the house. The inside of the building was far more brightly-lit than the streets outside. A soft, white light was pouring out from somewhere above, illuminating everything around them.

"What..?" Zack asked.

They walked the winding path upwards, the light growing stronger as they grew nearer to its source. As they reached the top of the building, the three of them stopped as one.

Sephiroth's jaw didn't quite drop, but it was a near thing.

"Wow," Zack said, "This was here all along? Seriously?"

The fish statue had dropped away; where it had gone, Sephiroth didn't know. In its place was a staircase made of shimmering glass. Each step was suspended, seemingly weightless, in the air. It spiralled down into a cavernous open space, the bottom so far below that Sephiroth could only make out a massive underground lake and the faint shapes of intricate and enormous buildings.

"So this is true Cetra architecture…" Lucrecia murmured. "How amazing." She leaned into the hole and gazed out across the structures below. "It must be a temple of some sort."

Sephiroth walked cautiously onto the first step. It held his weight easily, without so much as a shift. Apparently, this place was built to last.

"Stay close and keep your weapons at ready," he said. "We'll be exposed going down."

"Right," Zack said, shifting the Buster Sword in his grasp. Vincent brought his firearm into a ready stance and Lucrecia slid two green materia into the bracer on her arm.

They descended together. They had to step cautiously, both because danger could come from any angle and because there was no telling how much weight each step could hold. Sephiroth was acutely aware that at any moment their floor could drop out from underneath them. And all the while the pain in his head was building.

Zack was jumping the gap between two of the steps when he gasped, stumbled, and nearly fell into the void. Sephiroth lunged forward and hauled him backwards using a handful of his shirt.

"What are you _doing_?"

Zack's eyes were wide. "Look!"

Sephiroth followed the direction of his gaze.

The Cetra had built an altar of some sort that stretched above and across the surface of the lake. It was made of dark gray stone and delicate glass carved in a flower-like design. In its center, lying on the ground, was Aerith.

She was unconscious or dead, Sephiroth couldn't tell which. It meant trouble either way.

The presence of Jenova was hummed in his head. If she was dead, there could be only one culprit.

If they had failed to defeat Jenova-

If _he_ had failed to defeat her-

and Aerith had been killed as a result, then he was to blame.

"Sephiroth, come on!" Zack said. "We have to get down there."

He tried to dash past Sephiroth, but Sephiroth grabbed another handful of his shirt and hauled him backwards.

"What are you doing?" Zack snapped, wild-eyed and frantic.

They were still nearly a mile above the ground. There was no time to waste running down the stairs, and the danger of an ambush at their bottom was far too great.

"Trust me," Sephiroth said. "Please."

He didn't expect the words to make much difference, but to his surprise Zack stilled in his grasp. He stared at Sephiroth a long moment.

"Okay."

Sephiroth released him. Zack took a step back and ran a hand through his hair. "...Sorry."

"What's going on?" Lucrecia glanced over the edge carefully; Sephiroth wasn't sure how enhanced her eyesight was, if it all.

"There's a woman down there." Vincent answered. "Aerith?"

Sephiroth nodded. "You two, continue down the stairs. Rejoin us at the bottom as soon as you're able. Zack and I will take another way down."

A much, much more dangerous way, and that was saying something. But they were quickly running out of time.

"Be careful," Lucrecia said.

"Of course."

Sephiroth moved next to Zack and slipped Zack's arm over his shoulder.

"Hold on tight," he said.

"Hold on-?" Zack's question was quickly cut off as Sephiroth threw himself off the edge of the staircase.

They fell quickly. The water below was placid and dark; he could only hope it was as deep as it seemed. His heart was racing almost as quickly as the wind that whipped around them, but he ignored his physical reactions and concentrated on the materia in his bracer. He would have to time this very carefully.

"Holy _shit_!" Zack snarled in his ear.

The lake was nearly upon them. No time to second-guess.

Sephiroth cast.

* * *

(Comments and constructive criticism are always appreciated! Also, enormous thanks to my beta, Hokuto. Next chapter will be up sometime next week!)


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